(a) Field of the Invention
This invention relates to an electrically-controlled locking arrangement for the lock mechanism of a commercial vehicle load space door. Increasingly, such a lock mechanism is configured as a so-called slamlock, described in more detail below.
(b) Description of the Prior Art
A commercial vehicle such as a delivery van or truck having a closed load space provided with at least one access door normally has a lock mechanism arranged to allow locking of the door in a closed position.
A known form of door lock mechanism has a housing which is secured to the vehicle door by way of security bolts which cannot be released externally of the door. A hook member is rotatably mounted within the housing and projects therefrom for engaging an external catch member provided for example on a frame for the door or on a second door leaf in the case of a commercial vehicle access opening closed by a pair of hinged doors. A handle is coupled to the hook member to effect movement thereof between its open and closed positions. The hook member may be spring-biased to the closed position but is profiled such that closing the door automatically moves the hook member to its open position by interaction with the catch member, the spring then moving the hook member back to its closed position when the door is fully shut.
A lock mechanism as just described may be configured to have an automatic locking characteristic—i.e. configured as a so-called slamlock. This is arranged so that if the door is slammed shut, the lock automatically locks the door shut whereafter the door can be opened only by the use of an appropriate key. Such slamlocks are widely used on commercial vehicle hinged or sliding doors as well as on roller shutter doors and have the advantage that they provide security against opportunist theft from a vehicle left with the door closed but not locked.
A known form of commercial vehicle slam-lock mechanism may have a locking dog within the housing and which is movable between a locked setting and a free setting. When the locking dog is in its locked setting, the hook may be moved to its closed position if it is not already in that position, and the dog is then engaged with a detent provided on the hook member or a component coupled thereto such as the handle or a shaft carrying the hook member. When the dog is in its free setting, disengaged from the detent, the handle may be used to move the hook member between its open and closed positions at will. Typically, a mechanical key-operated lock is associated with the dog, such that the dog may be moved to its free position only by use of the key, whereby the handle may be used to move the hook member to its open position to allow opening of the door.
A commercial vehicle lock mechanism as described above, whether configured as a slamlock or not, will hereinafter be referred to as “a lock mechanism of the kind described.”
Increasingly, tracking systems for example employing GPS are being used on commercial vehicles such that the whereabouts of a vehicle is known at all times. Enhanced tracking systems may be arranged so that the opening of the load space door may be permitted only when the vehicle is at a pre-defined location, such as at a warehouse or retail outlet, where goods are to be unloaded from the vehicle. To this end, there is a demand for an electrically-controlled locking arrangement for a lock mechanism of the kind described, whereby the lock mechanism may be released to allow the load space door to be opened only when an appropriate control signal is supplied to the lock mechanism.
Many lock mechanisms of the kind described have a housing which has been designed to accommodate the components of the lock mechanism and there is very little free space within that housing for electrical control mechanisms able to lock the handle or the hook member in the closed position. As such, it is known to provide a second housing arranged for mounting on a door adjacent the housing of a lock mechanism of the kind described, the second housing having supported therewithin appropriate electrical control gear and mechanisms coupled to the lock mechanism of the kind described whereby the operation of the lock mechanism may be controlled. In this way, operation of the handle to release the lock mechanism and allow the door to be opened may be inhibited other than when the vehicle is, for example, at a destination pre-loaded into the system.
The fitting of such a second housing for electrical control gear and the coupling of the mechanisms within that second housing to the lock mechanism of the kind described is difficult and time consuming and moreover requires careful setting-up to ensure proper operation. In addition, the linkage between the mechanisms of the two housings may be open to abuse, so inhibiting the effectiveness of the security which otherwise could be achieved.